Quarter	Millions of US Dollars
1998-01-01	-14289
1998-04-01	17237
1998-07-01	36481
1998-10-01	-118600
1999-01-01	-29352
1999-04-01	-21598
1999-07-01	-4938
1999-10-01	47116
2000-01-01	-66477
2000-04-01	4528
2000-07-01	-34178
2000-10-01	32970
2001-01-01	9780
2001-04-01	17524
2001-07-01	-31662
2001-10-01	-26192
2002-01-01	-35018
2002-04-01	7744
2002-07-01	-17919
2002-10-01	16103
2003-01-01	-31612
2003-04-01	-13434
2003-07-01	-47129
2003-10-01	151
2004-01-01	-16619
2004-04-01	-6741
2004-07-01	-12223
2004-10-01	6111
2005-01-01	-30432
2005-04-01	16254
2005-07-01	-13065
2005-10-01	-184723
2006-01-01	-52315
2006-04-01	2245
2006-07-01	9247
2006-10-01	13826
2007-01-01	-12842
2007-04-01	22731
2007-07-01	7509
2007-10-01	52415
2008-01-01	-25931
2008-04-01	15021
2008-07-01	-3133
2008-10-01	8799
2009-01-01	-24457
2009-04-01	22291
2009-07-01	-26882
2009-10-01	17667
2010-01-01	-48146
2010-04-01	37737
2010-07-01	-13612
2010-10-01	12549
2011-01-01	-37126
2011-04-01	13671
2011-07-01	-7181
2011-10-01	4644
2012-01-01	-32620
2012-04-01	10886
2012-07-01	-8660
2012-10-01	5177
2013-01-01	-31100
2013-04-01	6751
2013-07-01	-7691
2013-10-01	9480
2014-01-01	-26194
2014-04-01	10446
2014-07-01	-2297
2014-10-01	10223
2015-01-01	-20548
2015-04-01	-2693
2015-07-01	-7553
2015-10-01	8224
2016-01-01	-12622
2016-04-01	44078
2016-07-01	-3612
2016-10-01	13406
2017-01-01	-21947
2017-04-01	12078
2017-07-01	-21486
2017-10-01	14539
2018-01-01	-24147